Hi, have a look at this tutorial for help:

http://wiki.debian.org/NvidiaGraphicsDrivers

I now have Nvidia acceleration but all I did was run synaptic then installed following packages:
nvidia-kernel-source
nvidia-settings
nvidia-glx
nvidia-kernel (matched against my kernel version)

You will find that synaptic automatically fills in the dependencies for you.

After that I manually edited my /etc/X11/xorg.conf file with changes as follows

--in module section--
Load "dbe" # Double Buffering Extension, very important.
Load "glx" # GLX Extension.


--in device section change driver from nv to nvidia as below

Section "Device"

### Available Driver options are:-
# sw_cursor is needed for some ati and radeon cards
# The following line is auto-generated by KNOPPIX mkxf86config
# Driver "nvidia"
# BusID "PCI:1:0:0"
Identifier "Card0"
Driver "nvidia"
VendorName "Sparkle"
BoardName "Geforce 5700 Ultra"
EndSection


Restarted X server.

When things go wrong, look for clues in var/log/Xorg.0.log or /var/log/messages, chances are the nvidia module may not have been loaded.
You can also try modprobe nvidia (as root) to prove this and
lsmod | grep nvidia
(to check if nvidia module has loaded)
Hope that helps